The present invention relates to intraocular lenses (IOLs). More particularly, the present invention relates to IOLs that provide accommodating movement in the eye.
The human visual system includes the eyes, the extraocular muscles which control eye position within the eye socket, the optic and other nerves that connect the eyes to the brain, and particular areas of the brain that are in neural communication with the eyes. Each eye forms an image upon a vast array of light sensitive photoreceptors of the retina. The cornea is the primary refracting surface which admits light through the anterior part of the outer surface of the eye. The iris contains muscles which alter the size of the entrance port of the eye, or pupil. The crystalline lens has a variable shape within the capsular bag, under the indirect control of the ciliary muscle. Having a refractive index higher than the surrounding media, the crystalline lens gives the eye a variable focal length, allowing accommodation to objects at varying distances from the eye.
Much of the remainder of the eye is filled with fluids and materials under pressure which help the eye maintain its shape. For example, the aqueous humor fills the anterior chamber between the cornea and the iris, and the vitreous humor fills the majority of the volume of the eye in the vitreous chamber behind the lens. The crystalline lens is contained within a third chamber of the eye, the posterior chamber, which is positioned between the anterior and vitreous chambers.
The human eye is susceptible to numerous disorders and diseases, a number of which attack the crystalline lens. For example, cataracts mar vision through cloudy or opaque discoloration of the lens of the eye. Cataracts often result in partial or complete blindness. If this is the case, the crystalline lens can be removed and replaced with an intraocular lens, or IOL.
While restoring vision, conventional IOLs have limited ability for accommodation (i.e., the focusing on near objects). This condition is known as presbyopia. To overcome presbyopia of an IOL, a patient may be prescribed eyeglasses. Alternative attempts in the art to overcome presbyopia focus on providing IOLs with accommodation ability. Accommodation may be accomplished by either changing the shape of at least one optic surface of the IOL, by moving the IOL along its optical axis, or some combination of the two. These and similar approaches for providing accommodation are disclosed, for example, in the following U.S. patents and patent applications, all of which are herein incorporated by reference: U.S. Pat. Nos. 4,373,218; 4,601,545; 4,816,031; 4,892,543; 4,994,083; 5,066,301; 5,108,429; 5,171,266; 5,203,788; 6,176,878; 6,406,494; 6,443,985; 6,599,317; 6,616,692; 6,638,305; 6,645,246; 2003/0060881; 2003/0158599; 2004/0034415; 2004/0082993; 2005/0131535; and U.S. patent application Ser. No. 09/656,661, filed in Sep. 7, 2000.
Despite these various devices and method of providing accommodation, there continues to be a need, to provide new IOLs with enhanced accommodative capabilities.